Gear shaft assembly

ABSTRACT

A gear shaft assembly is disclosed which utilizes a hollow splined shaft having a sliding worm gear sleeve splined thereon engaged with a driven gear. The splined shaft has clutch members at each end, engageable at one end with a motor shaft and at the other end with a manual operator shaft. A sliding rod assembly in the hollow shaft prevents simultaneous engagement of the splined shaft with the motor shaft and the manual operator shaft.

BACKGROUND OF THE INVENTION

In a large number of manufacturing processes utilized in industries suchas petrochemicals and food processing, the move toward automation hasresulted in the necessity for applying motorized power sources to thecomponents of those manufacturing processes. One of the largest and mostcritically needed areas of motorized operation is in the opening andclosing of valves such as gate valves, butterfly valves, plug valves,and ball valves.

The prior art has provided motorized valve operators which primarilyutilize electric motors operating through worm gear assemblies with gearreduction to move the gate valve stem vertically and rotate the valvestems of butterfly and plug valves. The prior art motorized valves havebeen further automated by the provision of torque sensitive cut-off andreversing switches to shut the actuator motor off before the valve isproperly closed. In addition to the automatic operation, a back-upsystem of manual operation must be provided for the situation where apower loss or motor failure has occurred.

The disadvantages suffered by the prior art valve actuators arise in thestructure of the two above-mentioned features, the torque cut-off switchand the manual operation feature. The prior art devices utilize a typeof torque sensing system such as a coil spring or Belleville springsinterconnected with the worm gear assembly such that when the gate valveis closed and resistance to further movement begins to increasedrastically, the spring system is compressed to a point that a switch isactuated. This cuts power to the actuator motor and the motor slows andstops.

The problem that arises with this type of system is that a correctcalculation of the closing torque that will be obtained is not possiblewith any degree of accuracy because of the high rotational inertia inthe motor after electric power is shut off. Thus, the only method ofgetting the proper closing torque is through a trial and error processon each individual motorized operator because of the large number ofvariables involved, such as motor size, motor speed, total rotationalmomentum, required seating torque, gear reduction ratio, stem speed,gear masses, and others. As a consequence of this inaccuracy, severedamage can occur to the valve components from inadvertentover-tightening.

A second disadvantage suffered by prior art devices involves theprovision for switching the actuator from automatic to manual operation.These devices provide a separate lever and gear assembly in theactuator. This elaborate system begins with an external shifting leverand includes several shafts and sliding gears for shifting the mode ofoperation. Unfortunately, the mere inertia and complexity of this systemmay prevent its successful operation when it is needed the most. A smallamount of dirt, sludge, or corrosion can render the shifting mechanisminoperable and the valve will not be operable until either the motorizedoperation is restored or the actuator can be disassembled and repaired.Also, the nature of the manual lever system requires that the actuatorbe placed in an easily accessible location.

The present invention overcomes these serious disadvantages and otherdisadvantages of the prior art by providing a motorized valve actuatorutilizing electrical and mechanical simultaneous motor disengagement andautomatic switching from motor operation to manual operation and backagain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate a cross-sectional view of a first embodimentof the invention.

FIG. 2 is a partial cross-sectional axial view taken at line 2--2 ofFIG. 1A.

FIG. 3 is an axial cross-sectional view taken at line 3--3 of FIGS. 1Aand 1B.

FIGS. 4A and 4B illustrate a partial cross-sectional view of theinvention of FIGS. 1A and 1B rotated approximately 90° therefrom.

FIGS. 5A and 5B illustrate a cross-sectional view of a second embodimentof the invention.

FIG. 6 is a partial axial view of the second embodiment taken at line6--6 in FIG. 5A.

FIGS. 7A and 7B are detailed views of the tripping mechanism of FIG. 5Bat line 7--7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1A and 1B, which when connected at common breakline a--a form a cross-sectional illustration of the valve actuatormechanism 10. The actuator mechanism 10 has a stem assembly 11, a motorsection 12, a hand wheel assembly 13 and a spring cartridge assembly 14.

The electric motor assembly 12 has an outer housing 15 and a motorstator assembly 16. The stator assembly 16 is mounted in housing 15, anda rotor assembly 16a is mounted on a rotatable shaft 17 which is carriedby upper roller bearing 18 and lower roller bearing 19. The stator 16encloses an annular space 20, and in close proximity thereto is locateda sliding sleeve 21 mounted in a stationary electromagnetic shieldsleeve 22. The sliding sleeve 21 is of a magnetic substance such as ironor steel and has threaded therein a plurality of elongated stud members23.

At the opposite ends of studs 23 is a stud plate 24 securedly attachedto the studs by threaded locknuts 25. A first section of spreading rod26 having a threaded end 26a extends through hollow shaft member 17 andstud plate 24 and is tightly secured to plate 24 by a pair of lockingnut sets 27 and 28. A helical coil spring 29 abuts stud plate 24 and aninternal web surface 30 of housing 15. The action of coil spring 29 isto continuously bias stud plate 24 downward thereby maintaining slidingrod 26 in its lowermost position.

At the upper end of housing 15 is an internal wall section 31 whichprovides support for bearing 18 and through which projects the upper endof shaft 17. The projecting end of shaft 17 has a splined section 32formed thereon and on which is slidingly located a jaw clutch member 33.Jaw clutch 33 is securedly attached to spreading rod 26 by means such aswelding 34.

Sliding movement of the motor shaft 17 is prevented by abutment ofshoulder 17a with the inner race of bearing 18. Likewise, a shoulder 17bprevents movement of shaft 17 in the opposite direction by abutment withthe inner race of bearing 19. Spreading rod section 26 may slidecoaxially inside shaft 17.

The motor housing 15 is attached by means such as bolts to an actuatorgear housing 35 containing a second spreading rod 36 which is incoaxially aligned abutment with lower rod section 26. Rod section 36passes through a jaw clutch 37 held in web plate 38 in rotatablerelationship therein by a ball bearing assembly 39. The jaw clutchsleeve 37 has an upwardly extending shaft section 40 having a wormsection which comprises a continuous helical tooth 40a formed on theouter surface thereof. A position switch gear shaft 40c extends behindworm section 40a and has secured thereon in engagement with worm 40a aposition switch worm gear 40b (see FIG. 4A). Rotation of shaft 40rotates gear 40b and shaft 40c which are operably connected to aposition-limit switch (not shown), which switches are known in the art.This switch governs valve travel in the opening and closing directionsand regulates the position indicator lights. When a position-seatedvalve such as a butterfly or plug valve is being operated, rather than atorque-seated valve such as a gate valve, the position-limit switch isadvantageous for shutting off the motor and reversing the direction oftravel. Basically, the position-limiting switch tracks the number ofrotations of the shaft 40 and its direction of rotation to monitor valveposition.

Above worm 40a, shaft 40 has short external splines 41 formed thereon. Ahelical worm 42 having internal splines 43 is slidably located on thesplined portion of shaft section 40. Worm 42 has a continuous helicaltooth 42a located externally thereon. Worm 42 is in engagement with acylindrical, driven, worm gear sleeve 44 which is located in slidingrelationship around a stem 45. Driven worm gear sleeve 44 has aplurality of longitudinal gear teeth 44a formed on the external surfacethereof and a pair of upwardly extending lugs 46 and 47 extending upwardpast the ends of teeth 44a. The lugs are arranged to contact a pair ofabutment lugs 48 and 49 formed on stem 45.

The upper end of worm 42 extends into a spring cartridge base 50 and haslocated thereon a ball bearing assembly 51 secured by a threaded nut 52.Bearing assembly 51 allows rotation of sleeve 42 within base member 50.The upper extended portion of shaft 40 passes slidably through thesleeve of worm 42 and extends upward in housing 35. A third spreadingrod 53 extends through the center of hollow member 40 protrudingslightly past the upper end thereof. A jaw clutch 54 is secured on theend of shaft 40 by means such as a spline or keyway 55. The jaw clutchis retained by snap rings 56 and 57.

A mating jaw clutch 58 is arranged in slidably abutting relationshipwith clutch 54 such that engagement of the two clutch members can beaccomplished. Clutch member 58 is slidably and coaxially located on asplined shaft 59 and a fourth spreading rod 60 passes through the centerof hollow shaft 59 extending into abutting relationship with rod 53. Rod60 has an enlarged head section 61 at the lower end for abutment withrod 53. A retention washer 62 is located above head 61 and in abutmenttherewith for preventing rod 60 from sliding upward and out of shaft 59.

A helical coil spring 63 is located in compression inside a hollowrecess 64 in shaft 59. Spring 63 provides a continual biasing actionagainst shaft 59, pushing retainer 62 downward against head 61 andtending to maintain rod 60 in its lowermost position. A raised annularshoulder 65 is formed externally on shaft 59 and seats in a recess 66formed in the upper housing 67 to restrain shaft 59 from upward passagetherethrough.

Actuator gear housing 35 has an upwardly extending spring cartridgehousing 77 formed integrally therewith. This housing is joined at 68 tothe upper wheel housing 67. Upper housing 67 is secured to springcartridge housing 77 by a number of threaded bolts 69 passing throughopenings 70 and threadedly engaging housing 77 in threads 71.

A manual operating wheel 72 is attached to shaft 59 and prevented fromrotating thereon by key means 73 fitting in corresponding grooves formedin shaft 59 and the internal surface of wheel hub 72a. A snap retainerring 74 prevents wheel 72 from sliding off of shaft 59. The upper end ofshaft 59 extends through the hub 72a of wheel 72 almost flush with theupper surface thereof. Shaft 59 has an enlarged opening 75 formed at theupper end for receiving the upper end of rod 60 which contains a nut 76threaded thereon.

A spring loaded lockout mechanism 80 is provided with the manual wheelassembly and consists of a sliding lock member 81 located in hub 72passing through an opening in the upper end of shaft 59 and arranged tobe projected inward below nut 76 to prevent further downward movement ofrod 60. An intermediate threaded sleeve 82 is threaded into hub 72a andcontains a helical spring 83 compressed therein. Locking pin 81 is inabutment with spring 83 and has a reduced diameter pin shaft 84extending outward through threaded sleeve 82. A crossbar 85 is securedin narrow pin shaft 84 and has a thumb cap 86 located thereon. Theintermediate sleeve 82 has a transverse groove 87 which allows the pinassembly to be secured in its outward, nonlocking, retained position bypulling cap 86 to the right and rotating 90° to seat crossbar 85 ingroove 87. To return to locking action, crossbar 85, pin 81, and shaft84 are released from groove 87 and allowed to slide radially inward,whereupon it will automatically move into a locking position below nut76 when the nut has moved upward sufficiently to pass above locking pin81. FIG. 1A shows the mechanism in its automatic locking setting. Thelocking mechanism may be neutralized by pulling outward on cap 86,rotating 90° and reseating locking bar 85 in groove 87.

A pair of spring compression plates 78 and 79 are located insidecartridge housing 77. Lower plate 79 is slidably located above cartridgebase 50 on top of circular snap ring 88. Two sets of helical compressionsprings each comprising three equispaced coil springs are locatedbetween plates 78 and 79. The first set of springs 89 are located aroundbolts 90 in encircling relationship therewith. Each bolt 90 is locatedinside an enlarged bolt head opening 98 located in upper cartridge plate125. Bolt 90 passes through a bolt passage 95 in the spring compressionplate 78 and extends downward inside coil spring 89 and bolt liner 93.The threaded end 91 of bolt 90 is threadedly engaged in spring cartridgebase 50. Bolt 90 passes through bolt passage 92 in the lower compressionplate 79.

A second set of three helical coil compression springs 103 is alsolocated in compression between upper and lower compression plates 78 and79 equispaced between each of the coil springs 89. A spring stud 101passes coaxially through each coil spring 103 and is threadedly engagedat 106 in upper plate 125. A locknut 107 further secures stud 101against movement with respect to plate 125. Stud 101 extends downwardthrough a stud passage 105 formed in upper compression plate 78, throughthe spring guide 104, through a stud passage 102 formed in lowercompression plate 79 and into a cylindrical opening 99 formed in base50. An enlarged cylindrical piston section 100 is formed on the lowerend of stud 101 for sliding engagement in cylinder 99. Passage 102 isinsufficient to allow movement therethrough by piston 100. Theconstruction of each bolt and spring assembly of the three member set isidentical to that illustrated at 89 and 90. Likewise, the assembly ofeach stud and spring assembly in the three member set is identical tothat disclosed at 101 and 103.

Upper plate 125 is tightly secured to the upper portion of cartridgehousing 77 by a plurality of bolts 109 passing through plate 125 andthreadedly engaging in bore 108. The bolts 109 have enlarged heads 110for abutment with washers or directly with plate 125. An inwardlyprojecting annular shoulder 111 is formed inside on the wall of housing77 for receiving plate 125 in abutment therewith.

Referring now to FIG. 2, an axial cross-sectional view of thearrangement of bolts and studs described above in the cartridge housingis illustrated. Each of the bolts and studs 90 and 101 are located in analternating circular pattern as shown. The four bolts 69 securing theupper housing 67 to the cartridge housing 77 are shown in cross-section.The four bolts 110 securing the upper plate 125 to the annular shoulder111 are shown spaced from bolts 69.

FIG. 3 illustrates a partial cross-sectional view of the assembly takenat line 3--3 of FIGS. 1A and 1B. In FIG. 3 spreading rod 36, splinedsection 40 and worm 42 are shown in axial cross-section. Alsoillustrated are the driven gear sleeve 44 with gear teeth 44asurrounding valve stem 45. Stem 45 is mounted in roller bearings 126 andsleeve 44 is located in axial abutment with the inner race 127a ofroller assembly 127.

Also in FIG. 3, microswitch 116 is shown and a second microswitchassembly 116' is drawn-in in phantom. Each microswitch assembly isarranged to provide a sensing and switching function in one direction ofmovement of the spring cartridge assembly. Thus, switch 116 is inoperating engagement with wedge surface 113 and the second switch 116'will be contacted with a second wedge surface having a surface taperedin the opposite direction to surface 113.

FIGS. 4A and 4B, when joined at common line b--b, comprise across-sectional illustration of the invention of FIGS. 1A and 1B at a90° orientation therefrom. The Figure further illustrates the relationbetween the valve stem 45, gear sleeve 44 and gear ring 44a. In thisFigure, similar numbers indicate similar structure with respect to FIGS.1A through 3.

In typical operation, the valve actuator mechanism 10 is energized bysupplying an electric power source to the motor 12. As this power sourceenergizes motor 12 an electromagnetic field is generated around thestator. This strong magnetic field draws sleeve 21 into space 20 andinto contact with the stator. This in turn moves stud members 23 andstud plate 24 upward simultaneously therewith. This movement of plate 24slides spreading rods 26, 36, 53, and 60 upward. This serves to move jawclutch 33 into engagement with clutch 37 while simultaneously pushingjaw clutch 58 out of engagement from jaw clutch 54. This spacing of thetwo pairs of clutches is such that clutches 58 and 54 will be completelydisengaged before clutches 33 and 37 begin engagement.

Likewise, with this shifting movement of the spreading rods, therotational force imparted by the motor assembly 12 is transferred toshaft 17 which in turn moves through splines 32, the jaw clutch 33.Since clutches 33 and 37 are engaged, clutch 37 and the upward extendingshaft 40, which is an integral part thereof, also begin to rotate. Therotation of shaft 40 operates through splines 41 and 43 to rotate worm42. This in turn drives the driven gear ring 44 until the lugs 46 and 47impact the valve stem lugs 48 and 49 thereby imparting a sufficienthammer force to the stem to begin movement of it in case it has becomestuck or frozen by corrosion or sediment.

The motor will continue to rotate the valve stem 45 through theaforementioned clutch and gearing system until that point when the valvestem has reached the end of the desired travel. At this point, the valvestem will begin to tighten at a sharp rate and resistance to furtherrotation will increase to the point that further rotation of shaft 37will force the worm 42 to slide upward along shaft 40.

This movement will be transferred through the bearing assembly 51 andinto base 50 and spring compression plate 79. Movement upward of theseelements will serve to compress the six helical springs 89 and 103. Thiscompression will occur against upper plate 78. Bolts 90 will move freelyupward through opening 98 and studs 101 will remain stationary as thelower section 100 thereof will be allowed to slide in opening 99 as basesection 50 moves upward thereby. Movement upward by plate 78 isprevented by abutment with upper plate 125 which is securely heldagainst shoulder 111 by bolts 109.

It should be noted that, as previously mentioned, clutches 58 and 54 arecompletely disengaged before any engagement of clutch 33 and 37 areachieved. This serves to disengage the manual valve opening mechanismconsisting of the hand wheel 72 and a splined shaft 59 which iscontinuously engaged in clutch 58. Upward movement of the four spreadingrods serves to push the retention washer 62 upward by means of abutmentwith head 61. The snap ring 112 and the recessed shoulder above washer62 in clutch 58 serve to retain the washer tightly in the centralopening of clutch 58. Thus, when head 61 is pushed upward by rod 53 thismoves clutch 58 upward through abutment with washer 62.

Clutch 58 is provided with internal splines 58a which mate with externalsplines 59a on spline shaft 59. This splined arrangement allows slidingmovement of clutch 58 on shaft 59 but locks them together against anyrotational movement therebetween.

Upon reaching the proper seating or opening torque, the wedge surface113 will have moved under the contact button 118 a sufficient amount tocompress it into housing 117 thereby actuating a microswitch located at116. This is connected with the power source to motor assembly 12 and,upon compression of button 118 a predetermined distance by surface 113,power will be disconnected from the electric motor. When this occurs,the magnetic field in the stator assembly will dissipate instantaneouslyand sleeve 21 will no longer be held therein. Springs 29 will thus beable to force plate 24 back downward which in turn pulls spreading rod26 downward and simultaneously disengages clutch 33 from clutch 37.

The rotational inertia remaining in the heavy motor assembly will thusbe allowed to dissipate in a free wheeling manner and will not react onthe gear assembly to further increase the tightening torque on the valvestem. This instantaneous mechanical disconnect of the motor thus allowsthe person operating the valving system to carefully present the desiredseating torque without having to account for the additional torque addedby the rotational inertia of the driving motor.

When the actuator has moved the valve stem to the end of its travel, forexample, when closing the valve, and the switch system 116 hasdisconnected the motor, both mechanically and electrically, a secondcircuit may be provided in switch 116 to reverse the direction ofrotation of the electric motor for the next power cycle. Thus, when theoperating personnel wish to open the valve again, the power is merelyreconnected to the electric motor and the valve will be actuated in theopposite direction. Alternately, a switching circuit may be providedhaving markings thereon related to opening or closing, thus allowingoperating personnel to select the direction of travel for the valve.

In any case, upon disconnection of the motor from the actuating gearsand clutches, the manual operating system is automatically reengaged inthe actuating system. This occurs through the spring action of coilspring 63 which expands against washer 62 and slides clutch 58 backdownward into engagement with clutch 54. Thus, should the power fail orthe motor become inoperable, it will automatically disconnect theactuating mechanism from the motor drive end of the assembly and engagethe hand operated mechanism at the opposite end of the assembly.

The hand wheel 72 may be locked out of operation through the activationof the lockout arrangement 81. The cap 86 is rotated until the crossbar85 is in the position shown in FIG. 1A, thus allowing spring 83 to movemember 81 radially inward against nut 76. When power is applied to motorassembly 12, the action of the spreading rods upward will slide nut 76above member 81 allowing it to move in further against rod 60 below nut76. Thus, the manual operating wheel will be locked out regardless ofwhether the electrical drive system is operable or not. The manualsystem may be reengaged any time the power is off by pulling outward oncap 86 and rotating it 90° to seat crossbar 85 in the upper groove 87.This maintains member 81 in a position clear of nut 76.

When the valve actuating mechanism is reversed to move the valve stem inthe opposite direction as mentioned above by either of the alternatemethods, the electric power will be restored to the motor 12 which willthen be rotating in the opposite direction from that previouslydescribed. The magnetic field will again be instantaneously generatedaround stator 16 and in space 20 which will pull sleeve 21 against thestator, moving the spreading rods upward, disengaging clutches 58 and54, and shortly thereafter reengaging clutch 37 with clutch 33. Therotational force of the motor will then be imparted to the worm 42 whichwill in turn drive gear 44. Lugs 47 will rotate until they contact stemlugs 49 and impart an initial hammer blow to free the stem if stuck orfrozen. Movement of the valve stem will then commence. The motor willdrive through the gearing assembly until the valve stem reaches the endof its travel whereupon gear ring 44 will slow and eventually stop,thereby causing worm 42 to advance downward pulling its associatedinterconnected assemblies with it.

Thus, downward movement of sleeve 42 acting through nut 52 moves bearingassembly 51 and base plate 50 downward therewith. The lower compressionplate 79 is held against downward movement by its abutment with pistonends 100 on studs 101. Studs 101 are prevented from downward movement bytheir threaded engagement with plate 125 and by the presence of locknuts107. Downward movement of cartridge base 50 also causes downwardmovement of upper plate 78 through the action of bolts 90 which arethreaded into plate 50 and in abutment with upper plate 78. Thus, sincelower plate 79 is refrained from moving downward but upper plate 78 isbrought down by the action of bolts 90, a compression of the six helicalsprings 89 and 103 between the two compression plates is achieved. Thecompression of the six springs tends to absorb shock from the bearingcomponents and from the valve stem reaching its end of travel. Thesprings also tend to retard the downward movement of sleeve 42.

Upon reaching a certain amount of downward movement, the cammed surfacehaving an opposite slope to that of surface 113 engages thecomplimentary microswitch 116' which is similar in operation to switch116 except it operates for movement of the valve actuator in theopposite direction. When the cartridge assembly has moved downwardsufficiently to activate switch 116', power to the motor assembly 12will be disconnected and the magnetic field generated therein willsimultaneously be dissipated allowing spring 29 to move plate 24downward, disengaging clutches 33 and 37 and reengaging the manualactuating mechanism as previously described.

Adjustment of the closing or opening torque desired may be obtained to afine degree by the adjustment of switches 116 and 116'. This adjustmentis provided by rotating threaded sleeve 115 having internal and externalthreads thereon. Rotation of switch box 116 is prevented by the securingarrangement 119 and 120. Rotation of housing 117 is prevented by beingsecuredly attached to switch housing 116. A radial rotation arm 115a isformed on sleeve 115 so that sleeve 115 may be rotated clockwise orcounterclockwise to move housing 117 and contact button 118 inward oroutward with respect to wedge surface 113. A threaded lock screw 121 isengaged in the outer radial end of arm 115a and a flat circularcalibration ring 122 is provided around the periphery of the arc createdby rotation of arm 115a and sleeve 115. A number of setting holes 124are drilled in the flat calibration ring 122 which allow screw 121 to bethreaded thereinto to lock sleeve 115 in the desired position. Thetorque settings associated with each position 124 may be enscribed onring 122 which settings may be calculated or determined by experimentalmethods. Likewise, a similar structure is provided for switch assembly116' for operation of the valve stem in the opposite direction.

The advantages of the above described embodiment are numerous and areobvious in light of the description thereof. One of the main advantagesis the elimination of a complex parallel gearing and lever system fordisengaging the electric motor and engaging the manual hand wheel. Inthe present invention, the hand wheel and the motorized system are inthe same coaxial gear train. Likewise, no manual changeover from themotor to the hand wheel is required. When power is lost or motor failureoccurs, the motor is automatically disconnected and the hand wheel isautomatically engaged. Thus, the elimination of the separate shiftingmechanism found in the prior devices.

A second major advantage obvious in the invention is the elimination ofthe valve overtightening which occurs in the prior art devices from thedissipation of the rotational inertia of the drive motor. The prior artdevices utilize electric disconnect of the motor but dissipate therotational energy in the tightening operation. The present inventionprovides a simultaneous electric and mechanical disconnection of themotor to prevent any of the rotational inertia of the motor fromentering the tightening sequence after the preselected torque has beenachieved. This results in the ability to obtain a very accurate andprecise torque in the closing and opening of the valve.

A third advantage apparent in this invention is found in the spreadingrod principle which is a fail-safe design arranged to preventsimultaneous engagement of the actuator motor and the manual operationsystem. The total combined length of the spreading rods is justsufficient to prevent simultaneous engagement of clutches 33 and 37 andclutches 58 and 84.

Likewise, a feature is provided with this invention whereby the manualoperating system may be placed on automatic lockout for lockout at anytime power is restored to the motor. The disengagement of the hand wheelwill activate the lockout pin and the hand wheel will not bereengageable until the lockout has been manually reset to allow handwheel operation.

Another advantage of this invention is the provision of a multitude ofcoil springs 89 and 103 to replace the fatigue-prone Belleville springsystems of the prior art devices. The multitude of helical springs alsois advantageous over those prior art devices which utilize a singlelarge coil spring which itself is subject to failure. The provision of anumber of springs allows operation of the assembly even though one ormore of the springs may have failed.

The present invention also allows the retention of the conventional wormgear operation on the valve stem which is a gear reducing mechanism andwhich also is a self locking gearing system preventing loosening orbacking off of the valve after it has moved into the opening or closedposition.

One further advantage of the present invention is the ease with whichthe spring cartridge assembly may be removed for repair or replacementwith springs of different spring force constants. The spring cartridgeassembly may be removed by disassembling the bolts 69, 90 and 110.

Referring now to FIGS. 5A through 7B, an alternate embodiment of theinvention is disclosed. FIGS. 5A and 5B, when joined at common breakline c--c, illustrate a cross-sectional view of a valve actuatormechanism 200 which does not utilize the automatic switching featurefrom motorized operation to manual operation on power loss or motorfailure. The actuating mechanism 200 instead utilizes a switchingfeature that is hand-engaged rather than automatically engaged as inmechanism 10. In mechanism 200, many of the same components are utilizedfrom the actuator 10 and these components are numbered identically tothe corresponding components in FIGS. 1A through 4B.

In this invention, a standard electric motor 212 is utilized which doesnot feature the magnetic engagement operation as utilized in the firstembodiment. The motor 212 has a stator assembly 213 secured inside themotor housing 212a. A rotor assembly 214 is secured on a rotating shaft214a which is supported by ball bearings 215 set in web structure 216.The upper end 214b of shaft 214a has external splines 214c locatedthereon which are engaged in the internal splines of jaw clutch 217. Araised shoulder section 214d is formed on shaft 214a below splinesection 214c. This shoulder receives a retention disc 218 having astepped outer perimeter 218a. A coil spring 219 encircles the lower endof jaw clutch 217 and engages in the stepped perimeter 218a of disc 218.Spring 219 is in compression and tends to bias jaw clutch 217 to slideupward on splines 214c.

A mating jaw clutch 37 is located above clutch 217 in a position to beengaged therewith. Clutch 37 has an upper extending hollow shaft section40 as described in the previous embodiment. A lower spreading rod 220 islocated in the central passage of clutch 37 and extends downwardlytherefrom to an enlarged abutment disc 221 formed at the lower end ofrod 220. Clutch 37 is rotatably secured in web plate 38 by ball bearingassembly 39.

The valve stem 45 and the driven worm gear ring 44 having lugs 47thereon are similar in construction to the corresponding elements of theprevious embodiment. A position-limit switch (not shown) is connectedvia shaft 40c and worm gear 40b (not shown) to a limit switch wormsection 40a formed on shaft 40 as described in the previous embodiment.Operation of this switch is also the same as in the first embodiment.Likewise, spline section 40 and worm 42 are similarly constructed.

A number of flat spacer discs 36a are located on top of rod 220 andcarry a second rod 222. Rod 222 extends upward above the upper end ofshaft 40. A jaw clutch 223 is securedly held on shaft 40 by means suchas snap rings. A keyway 224 locks jaw clutch on shaft 40 againstrotation thereon. A mating jaw clutch 225 is located directly aboveclutch 223 and is similarly secured to the hand wheel shaft 226 bykeyway 227 and upper and lower snap rings.

Hand wheel shaft 226 is slidably and rotatably mounted in upper housing228. A manual hand wheel 229 having a reenforced hub section 230 issecured on the upper end of shaft 226 by snap rings and rotation thereonis prevented by a keyway 231. A peripheral groove 232 is formed in shaft226 for receiving a spring loaded detent button 233. A pair ofmicroswitches 116 and 116' for sensing the opening and closing torque inthe valve stem are provided as described in the previous embodiment.

A pair of locking plungers 234 and 235 are located in threaded openingsin the wall 35a of the actuator housing. Each locking plunger is locatedradially outward from jaw clutch 217. Jaw clutch 217 has formed in theouter wall hereof a stepped perimeter section 217a. Each locking plungerutilizes a generally cylindrical housing 234a with a threaded section234b. The plunger body is hollow and contains a plunger rod 236 whichhas an abutment shoulder 236a thereon for preventing the rod fromsliding out of the end of housing 234a. A coil spring 237 is located incompression behind shoulder 236a and in abutment with threaded plug 238which is threaded into section 234b of the plunger housing. Plug 238 hasa bore passage therethrough for slidably engaging rod 236.

FIGS. 7A and 7B more particularly illustrate the structure of the twolocking plungers 234 and 235. FIG. 7B is a cross-sectional view of jawclutch 217 illustrating the peripheral step section 217a. It can be seenthat stepped section 217a contains a pair of diametrically opposedcammed shoulders 217b having an outer diameter identical to theoutermost diameter of jaw clutch 217. Thus, when jaw clutch 217 ispushed downward against spring 219, at least one of the locking plungers234 or 235 will engage in stepped shoulder 217a thereby locking jawclutch 217 in its disengaged downward position.

In FIG. 7A the means for disengaging the locking plungers isillustrated. This consists of a small offset 239 between the plungerrods of the two locking plungers 234 and 235. This offset occurs in theaxial direction corresponding to the longitudinal axis of shaft 214 androd 210. Thus, after the jaw clutch 217 has been manually disconnectedfrom clutch 37 by moving it backwards until locking plungers 234 or 235engage shoulder 217a, jaw clutch 217 will remain locked down until poweris restored to motor 212. Upon restoring power to the motor, jaw clutch217 will begin to rotate with rotation of the motor. At this time, theplunger rod 236 of the left-most locking plunger 234 will be compressedby engaging one of the cam shoulders 217b. Upon reaching the outermostdiameter on shoulder 217b, the locking action of plunger 234 will beneutralized and jaw clutch 217 will shift to the right by an amountequivalent to the offset 239. At this point, the jaw clutch will beengaged with locking plunger 235 and plunger 234 will no longer be ableto reengage in stepped section 217a.

Upon an additional 90° rotation of jaw clutch 217, plunger 235 willengage a cammed shoulder 217b and will be compressed unti it reaches theoutermost periphery of a cammed shoulder, and the jaw clutch will becompletely released to move upward and reengage clutch 37. The springaction of coil spring 219 automatically assures that this action willoccur in all instances when the electric motor is restarted unless oneof the operating personnel is still engaging the hand wheel andmaintaining it pushed inward in the mechanism. The results of the handwheel being engaged and power being supplied to the electric motor willstill not create a dangerous situation since the length of spreadingrods 220 and 222 has been adjusted precisely by the addition of spacerdiscs 36a to prevent simultaneous engagement of clutch 225 with 223 andclutch 37 with clutch 217.

The reengagement of power to motor 212 while the hand wheel is beingheld in place will merely allow the motor to rotate freely withoutengaging the actuating gear mechanism. When manual operation has beencompleted, releasing hand pressure on wheel 229 will allow spring 219 tomove jaw clutch 217 against end 221 of spreading rod 220. This abutmentwill move rods 220 and 222 upward against shaft 226 tending to bias itoutwards from housing 228. Spring detent button 33 will be compressedradially outward from groove 232 by this upward pressure and hand wheel229 will be moved outward disengaging clutch 225 from clutch 223.

Any time power failure occurs or motor 212 quits running for any reason,the manual engagement may be accomplished merely by pushing downward onhand wheel 229 until detent button 233 engages groove 232 indicating bya snapping feel and sound that the manual system is engaged. This willpress down on spreading rods 222 and 220 moving jaw clutch 217 downwardon splines 214b until one or more of the locking plungers 234 engageshoulder 217a and lock jaw clutch 217 in its disengaged position. Thehand wheel is then in a position through engagement of the upper jawclutches to rotate worm sleeve 42 to drive valve stem 45 by means gearring 44.

Operation of the torque control assembly comprising the six helicalsprings and their associated studs and bolts with switches 116 and 116'is identical to the operation of the identical components as describedwith respect to the first embodiment.

Thus, the advantages of the second embodiment include the elimination ofthe need for an independent gear and lever assembly for switching frommanual to motorized operation. A second advantage lies in the spreadingrod principle which prevents simultaneous engagement of the motorizedgearing with the manual gearing.

This invention is particularly suited in nuclear plants and criticalareas where speed of stem travel is very important. The use of thisinvention allows use of high speed motors to achieve a high stem speedfor rapid valve operation.

Other advantages include those found in the previous embodiment such aseasy removal of the spring cartridge assembly for maintenance orchanging of spring constants. Likewise, this embodiment offers theadvantage of precise control of predetermined valve seating torque.

Although certain preferred embodiments of the invention have been hereindescribed in order to provide an understanding of the general principlesof the invention, it will be appreciated that various changes andinnovations can be effected in the described valve actuator mechanismwithout departing from these principles. For example, whereas sixhelical compression springs are utilized in the spring cartridgeassembly, it is clear that other numbers and other types of springsmight be utilized. Also, it is apparent that different types of sensingswitches could be substituted for the spring button microswitches 116.Other changes would be apparent to one skilled in the art and thereforethe invention is declared to cover all changes and modifications of thespecific examples of the invention herein disclosed for purposes ofillustration which do not constitute departures from the spirit andscope of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A motorized gear-driveassembly comprising:motor means comprising an electric motor having anoutput shaft; a first clutch slidably located on said output shaft nearthe end thereof; a hollow gear-drive shaft coaxially aligned with saidoutput shaft and having a second clutch engageable with said firstclutch, and a third clutch at the opposite end thereof; manual operatingmeans having an output shaft coaxially aligned with said gear-driveshaft and having a fourth clutch slidable on said manual output shaftengageable with said third clutch; and, sliding rod means passingthrough said hollow shaft and arranged to prevent simultaneousengagement of said four clutches by abutment with said first and fourthclutches.
 2. The gear-drive assembly of claim 1 wherein said motor meanscomprises an electric motor having magnetic field generating meanstherein, and said sliding rod means further comprises magnetic actuatingmeans actuated by said generating means to slide said rod means intoabutment with said fourth clutch to disengage it from said third clutch.3. The gear-drive assembly of claim 2 further comprising spring biasingmeans tending to continuously bias said sliding rod means in a directionaway from said generating means and said fourth clutch means.
 4. Acoaxial shaft assembly for transmitting rotational motion, said shaftassembly comprising:first input shaft means rotatably mounted in ahousing wall and having a slidable engagement member on one end thereofsecured against rotation on said input shaft means; an intermediatedrive transfer shaft coaxially aligned with said input shaft means androtatably mounted in a housing wall; said transfer shaft having poweroutput gear means thereon, a central axial bore passage therethrough,and fixed engagement members at each end thereof; second input shaftmeans rotatably mounted in said housing wall at the end of said drivetransfer shaft opposite to said first input shaft, and having a slidableengagement member on one end thereof held against rotation thereon andarranged for engagement with an engagement member on said transfershaft; said input shafts and transfer shaft being coaxially aligned;and, sliding means inside said axial bore passage, having a lengthgreater than said transfer shaft and its fixed engagement members, inabutment with said sliding engagement members and arranged to preventsimultaneous engagement of said two sliding engagement members with saidfixed engagement members.
 5. The shaft assembly of claim 4 wherein saidgear means comprises a helical gear secured on said transfer shaft bymeans preventing rotation thereon.